Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          471        179 
1992          743        301 
1993         1308        487 
1994         1681        617 
1995         3072       1072 
1996         2980       1053 
1997         1866        644 
1998        21858       9277 
1999        13565       5200 
2000        38667      15986 
2001        39476      15335 
2002        33354      14658 
2003        57819      24058 
2004        46394      17800 
2005        81552      25104 
2006       105226      33770 
2007       192073      59360 
2008       112732      32272 
2009        93496      26347 
2010       135128      36704 
2011       158653      44000 
2012       149861      41521 
2013       221937      63228 
2014       565545     144075 
2015       798297     210061 
2016       660037     171514 
2017       555295     150345 
2018       352852      99126 
2019       866111     211430 
2020       619143     157607 
2021       834217     198113 
2022       622764     178254 
2023       560288     160256 
2024       620012     178622 
2025       206048      58882